Apparatus for atomizing and igniting substances



Jan. 17, 1956 w. B. SMITS 2,731,079

APPARATUS FOR ATOMIZING AND IGNITING SUBSTANCES Filed Jan. 22, 1953 2Sheets-Sheet 1 kiz'g wyrzs BEYE .5/1/ n5,

Jan. 17. 1956 w. B. SMITS 2,731,079

APPARATUS FOR ATOMIZING AND IGNITING SUBSTANCES Filed Jan. 22, 1955 2Sheets-Sheet 2 United States Patent APPARATUS FOR ATOMIZING AND IGNITINGSUBSTANCES Wytze Beye Smits, Voorburg, Netherlands Application January22, 1953, Serial No. 332,697

Claims. (Cl. 15828) The present invention relates to atomizing andigniting substances in a chamber having at least one hole, by means ofan'electric spark produced in the chamber. The energy of the sparkdrives the substance with great force out of the chamber through theholes, whereby it is atomized and ignited. This application is acontinuation in part of an application entitled, Process and Apparatusfor Atomizing and for Igniting Substances, Serial No. 37,904, filed July9, 1948, now abandoned.

Apparatus operating according to this principle in which a high tensionspark (500030,000 volt) or a series of high tension sparks is used foratomizing and igniting combustibles are known. However, the knownapparatus presents various objections. It is desirable for a goodoperation of the apparatus to use an electric discharge in which theelectric energy is liberated in the form of a spark in the shortestpossible time. The inductive or the inductive-capacitative dischargeobtained in the usual high tension apparatus cannot satisfy thisrequirement.

Furthermore, it is known that production of sparks is impeded if theelectrodes become fouled by carbon deposit or other similar deposit onthe insulation between the electrodes. Also great care must be taken tobe sure that all parts of the high tension'devices are well insulated.

The object of the present invention is to overcome these difficulties inthe known devices. In the present invention, the spark is obtained by acompletely or substantially aperiodic discharge of a condenser across aspark bridge. Investigations carried out by the inventor have led to thediscovery that, for a good atomization, accompanied by ignition, thetension at the spark gap need not bemuch higher than 3000 volts and, inmany cases, may even be considerably lower.

The chamber from which the substance is atomized, hereinafter to becalled spark chamber, is provided with a spark gap carrying device to becalled a spark plug, the electrodes of which extend into the chamber. Inthe chamber wall, one or more holes, connecting the chamber with itssurroundings, are provided through which the substance is ato'rnizedandwhich may be equipped or not with automatic or commanded closingdevices. Furthermore a duct from the supply of the substance to beatomized to the spark chamber has been provided through which thesubstance to be atomized can be fed to the spark chamber. The substancecan be conveyed to the spark chamber in any suitable way. In the case ofa suitable pump, by means of suitable pressure in the container, towhich the spark chamber is connected by a duct, by placing the containerin a higher position so that the liquid may reach 'the spark chamberunder the influence of gravitation, or by other means or combination ofmeans.

The invention also comprises filling and/or dosing devices for thesubstance to be atomized, actuated automatically-by the operation of thespark chamber. These filling and/or dosing devices are advantageouslyplaced in the vicinity'of the spark chamber. They consist substantiallyof a conveniently shaped non-return valve placed in a widened part ofthe duct through which the liquid reaches the spark chamber. Under theinfluence of the pressure urging the substance through the duct to thechamber, the non-return valve shuts off the supply of liquid to thespark chamber. Generating of sparks causes the pressure in the sparkchamber to rise to such a degree that the non-return valve is forcedback, and in its extreme position, closes the orifice of the upstreamsection of the duct. Thus, the liquid in the supply duct is preventedfrom being forced back by the overpressure developed in the sparkchamber. As soon as the pressure in the spark chamber has droppedsufiiciently, the valve returns to its original position. During thelatter movement, however, a predetermined quantity of liquid, exactlymeasured, enters the spark chamber, propelled partly by the head of theliquid, partly by the pump action of the valve, whereupon the processrepeats itself.

It is advantageous to supply the fuel through the spark plug to thespark chamber, the spark plug being provided to this end with suitableducts. These ducts may be either straight or screw-shaped. The lattershape has the advantage of opposing a high resistance to a backward flowof the liquid in the duct due to the rise of pressure in the sparkchamber when a discharge takes place. As the emptying of the duct ishereby reduced in certain embodiments, especially those working with lowdischarge frequencies, the non-return valve may be dispensed with. If anon-return valve is used, its useful life is prolonged by usingscrew-shaped ducts. Thus, the sudden pressure rise provoking the impactof the valve against the orifice of the upstream section of the duct isrestrained by the high resistance of the screw-shaped ducts.

In using fuels to be not only atomized but ignited as well, the sparkchamber should be so dimensioned that, in addition to the substance tobe ignited, a certain quantity of air, serving to start the ignition,should be present in the spark chamber. Satisfactory results have beenobtained by using 2 per cent by volume of oil and filling the remainderof the chamber with air. Thus, for a small chamber, only a few drops ofoil will be lying on the spark surface. The energy of the spark shouldbe adapted to the conditions and to the properties of the fuel.

It will be readily understood that it is also possible to atomize thefuel from the spark chamber only, and to ignite the fuel thus atomizedoutside of the spark chamber by any suitable means. This mayconveniently be effected by means of separate electric sparks.

Particularly favorable results are obtained in the embodiment whereinthe main discharge of the condenser is initiated by a surface creepagedischarge over the frontal surface of the spark plug between theelectrodes. The

discharging time of the condenser is extremely short, the

electric energy manifesting itself almost as an explosion in the sparkchamber. It will readily be understood that, even at relatively lowtensions at the spark bridge which may be considerably less than 3000volts, a discharge is obtained which will atomize the fuel and, ifdesired, ignite it with certainty. By using the condenser discharge, theduration of the spark is extremely short lasting for second. It has avery high temperature of about 3000" C. The force, energy, and rapidityof the spark is so great that'it will cause the fuel oil, for example,to be very rapidly atomized and ignited as if it were an explosion. Theexplosion, combined with the heat created, will force the atomized fuelthrough the chamber orifice and outside in an ignited condition.

with the drawings, the material will be semi-conductive,

or, in the case of a non-conductor, may be provided on Patented Jan. 17,

its frontal surface with a semi-conductive layer or will becomesemi-conductive in operation by deposits of car bon on the surface ofthe material. These alternatives can be used interchangeably as desired.

The process and apparatus according to the present invention, whereby afuel is atomized and ignited, can be used advantageously to ignite otherinflammable or explosive substances. Various embodiments can be given tothis apparatus. It is, however, advantageous to combine the spark plugwith the spark chamber to form one single unit which may be mounted andremoved as such. It is also advantageous to feed the ignition fuel inthe spark chamber through the spark plug as described above. The use oflow tension makes possible the use of an insulating layer separating theelectrodes of a very small thickness which, in many cases, need not bemore than 1 mm. Thus, the apparatus may have a substantially cylindricalshape of very small cross section so that the apparatus may be lodgedvery easily, for example, even in existing burners, withoutnecessitating important modifications of the burner. Such an ignitionapparatus may be placed axially in the burner in such a way that thespark chamber, being the extremity of the apparatus, is located withinthe cold core of the burner flame, but does not protrude past said core.Thus, a rapid and certain ignition of the burner is ensured withoutunfavorably influencing the form of the flame cone, which is often thecase with the usual ignition devices. At the same time, the life of theignition device is greatly prolonged, as it does not come in contactwith the hot part of the burner flame.

The invention will be further explained with reference to the drawings,representing several examples of embodiments. It will be understood thatthe invention is not limited to these examples, as other embodimentsfalling within the scope of the invention are possible.

Fig. 1 is an elevational view, partly in section and partly diagrammaticof the apparatus according to the invention with a possible arrangementof electrical connections;

Fig. 2 is an elevational view, partly in section of another embodimentin which a substance is atomized from a spark chamber and is ignited bya separate ignition device represented in the form of an electricalspark p Fig. 3 is an elevational view, partly in section of an apparatussubstantially as in Fig. 1, showing a filling and dosing device;

Fig. 4 is an elevati'onal view in section of another dosing device;

Fig. 5 is an elevational view, partly in section, showing a possibleembodiment of the spark bridge shaped as a spark plug;

Figs. 6, 7, 8, 9 and 10 are cross sections of the spark plug, showingvarious embodiments of ducts;

Fig. 11 is an elevational view, partly in section, of another embodimentof the spark plug, combined with the spark chamber;

Fig. 12 is a diagrammatic representation of a burner provided with theignition device according to Fig. 11;

Fig. 13 represents still another embodiment of a spark plug with theouter shell partly broken away in order to show screw-shaped ducts ofthe type represented in Fig. 9.

In Fig. l the spark chamber 1 is formed partly by a hollow body 5,partly by the active extremity 4 of the spark bridge shaped as a sparkplug. The spark chamher is provided with atomizing holes 2 and with aduct 3, to which the fuel supply duct is connected. The centralelectrode of the spark plug is electrically connected at 6 with acondenser 7 and with a current source 9 supply ing direct or rectifiedalternating current. The outer electrode of the spark plug is connectedover the mass of the body 5 and a switch 8 with the condenser 7 or thecurrent source 9, dependent upon the position of the switch. it will bereadily understood that the switch 8 may also be inserted in the line,connecting the points 6, 7 and 9. In the dotted position of the switch8, the condenser is charged, whereas the condenser discharges itselfover the spark bridge when the switch is in the position indicated bythe solid line. The self induction of the circuit being negligiblepermits an entirely or sub stantially aperiodic spark discharge.

Fig. 2 represents a similar device, differing, however, in that a secondspark plug 10 is used to ignite the substance atomized from the sparkchamber 1. It will readily be understood that the respective position ofthe spark plug 10 and of the atomizing holes should be such that thesubstance atomized from the holes 2 meets the spark of the spark plug10. Other parts in Fig. 2 corresponding to parts in Fig. l are indicatedby primed numerals.

Fig. 3 represents again the embodiment according to Fig. 1, but now incombination with a dosing device which automatically and periodicallysupplies a predetermined quantity of fuel to the spark chamber. Thesubstance to be atomized is supplied to the spark chamber 1A from thecontainer 17 through a duct 11, propelled by compressed air admitted tothe container by the duct 19. A cock 16' can be used to cut the duct 11from the container 17. Between the container 17 and the spark chamber1A, preferably as near as possible to the spark chamber, is placed adevice for automatically measuring the quantity of liquid introducedduring each cycle into the spark chamber. Said device consistssubstantially of a valve chamber 12, wherein a non-return valve 13, inthis embodiment a ball valve, is located. In the position indicated inthe drawing, the ball 13 closes the supply duct 3A to the spark chamber1 so that there is no connec-' tion between the container 17 and thespark chamber 1A. The electric discharge in the spark chamber provokes asudden increase of pressure forcing the ball 13 backward, which nowcloses the orifice 15 of the upstream duct 11. When the pressure in thespark chamber'd'rops again below that existing in the duct 11, the ball13 moves back again toward the seat 14 under influence of the pressureof the liquid. As the valve chamber 12 has a greater diameter than theball 13, there is a direct connection between the upstream duct 11 andthe duct 3A,

the ball moves from position 15 to position 14 so that,

during this period, liquid is admitted from the container 17 to thespark chamber 1A. The quantity of liquid supplied each time to the sparkchamber 1A depends, among other factors, upon the pressure in thecontainer 17, upon the diameter of the duct 14 and of the duct 3, uponthe length of the stroke of the ball 13, and upon the difference indiameter between the ball and the valve chamber 12. All of these factorscan be controlled so that it is possible to measure the quantity ofliquid to the spark chamber with every stroke. Other parts in Fig. 3corresponding to parts in Fig. 1 are indicated by the same numeral withthe letter A added.

Best results will be obtained if the amount of oil supplied each time isonly a few drops, approximately 2 per cent by volume of the chamber.

Fuel supplying devices such as that shown in Fig. 3 can be used with allof the spark plugs described herein.

Fig. 4 gives another embodiment of the non-return valve, here indictedat 20 and provided with two conical faces 21 and 22 closing the orifices14B and 15B of the ducts 3B and 1113 respectively. In the positionrepresented in the drawing, the valve is forced onto the seat 14 by thespring 23. Several guide wings 24 center the valve in the valve chamber.The space between the guide wings allows the liquid to flow from theduct 11B through the valve chamber 128 to the duct 3B in theintermediate positions of the valve. It will be understood that variousembodiments can be given to the valve and the valve chamber fallingwithin the scope of this invention;

Fig; 5 represents an embodiment of the invention in the form of a sparkplug. The spark plug consists substantially of a central electrode 29which can be connected to the electric conduit at 6, surrounded by arelatively thin insulating or semi-conductive layer 30, surrounded againby the outer electrode 31, the lower end of which may be provided with ascrew-thread. As mentioned above, it may be advantageous to feed thesubstance to be atomized through the spark plug to the spark chamber.Some embodiments of a spark plug provided with supply ducts are shown incross section in Figs. 6 to inclusive.

Fig. 6 represents a spark plug with a central electrode 29a providedwith a central bore 32 forming the duct. Other parts in Fig. 6 similarto corresponding parts in Fig. 5 are indicated by the same numeral withthe letter a added.

According to Fig. 7, one or more ducts are formed by grooves 33 runningalong the central electrode 29b so that said ducts are limited on oneside by the central electrode and on the other side by the spark bridge3012. Other parts in Fig. 7 similar to parts in Fig. 5 are indicatedwith the same numeral with the letter b added.

Fig. 8 is a similar embodiment differing, however, in that the supplyducts 34 in this case are disposed on the inner face of the spark bridge300. Other parts in Fig. 8 similar to corresponding parts in Fig. 5 areindicated by the same numeral with the letter c added.

According to Fig. 9, the ducts have been given the form of groovesdisposed on the outer circumference of the spark bridge 30d. Other partsin Fig. 9 similar to corresponding parts in Fig. 5 are indicated by thesame numeral with the letter d added.

Fig. 10 represents an embodiment in which the ducts 36 are disposed onthe inner side of the outer electrode 31c. This embodiment presents theadvantage that the spark bridge 30c is not submitted to tensile stressesdue to the pressure developed in the spark chamber 1 and transmitted tothe liquid filling the ducts, so that there is no danger of fracture. Anadvantage of the embodiments represented in Figs. 9 and 10 is that theliquid filling the ducts is not subject to electric tension as is thecase in the embodiment according to Figs. 6, 7, and 8 and that the duct11 need not be insulated. Other parts in Fig. 10 similar tocorresponding parts in Fig. 5 are indicated by the same numeral with theletter e added.

An embodiment of a spark plug with screw-shaped ducts 49 is representedin Fig. 13. It is easily to be understood that ducts of the type shownin Figs. 7, 8, 9, and 10 can be advantageously given a similardisposition. Other parts in Figure 13 similar to corresponding parts inFigure 5 are indicated by the same numeral with the letter g added.

Fig. 11 shows, partly in cross section, partly in elevation, a sparkplug having ducts as represented in Fig. 10, in which the extended endportion of the outer electrode constitutes the spark chamber. Thestraight central electrode 29 can be connected to the electric terminalat 6a. The central electrode is surrounded by a spark bridge 30fsubstantially having the shape of a thin hollow cylinder and consistingof an insulating and at least partly semiconductive material. The outerelectrode 37 likewise having substantially the form of a hollow cylinderis disposed around the spark bridge 30], the foremost end 38 projectingfrom the frontal faces of the spark bridge and of the core electrode andforming the spark chamber 39, from which substances may be atomizedthrough one or more holes 40. The outer electrode 37 is connected tomass 41 and by way of the latter to the electric circuit. The insidesurface of the electrode 37 is provided with ducts 36a which areconnected with the supply duct 3a. As a consequence of the low tensionsused, it is possible to give to the device a small outer diameter, asthe body 30 need have only a very reduced thickness. This allows theconvenient use of the device as an ignition apparatus for burners.

The fuel may be supplied by a device such as that shown in Fig. 3 anddescribed above.

In operation, oil is supplied to chamber 39 in small doses, throughducts 36a in such a manner that suflicient air will remain in thechamber to support combustion.

Since use is made of a periodic condenser discharge at about 3,000volts, the ignition spark is extremely short and is explosive in nature.Upon creation of the spark, a very strong flame explodes through orifice40 and may be used for igniting combustibles in a burner or the like.After the discharge, air will penetrate again into chamber 39, as no oilor no gases will be present in the chamber after the explosion.

In Fig. 12, a section of such a burner has been represented in a verysimplified way. 42 is the ignition device placed centrally in the burner43. 44 is the fuel duct of the burner, whereas combustion air issupplied through 45. The burner is started by means of the ignitiondevice 42, the foremost end 46 of which does not project beyond the coldcore 47 of the flame 48 during the operation of the burner.

I claim:

1. A device for atomizing and igniting a liquid fuel substance andcomprising means forming a pressurizing chamber having at least onenarrow orifice connecting the interior of said chamber with thesurrounding atmos phere and permitting entrance of atmospheric air intothe chamber, means for supplying to the chamber the liquid fuelsubstance to be atomized and ignited, said chamber and said orificebeing so proportioned and arranged as to allow the simultaneous presenceof air and fuel substance, a substantially non-inductive spark bridge insaid chamber and adjacent said fuel supplying means to contact a portionof said fuel, and a uni-directional capacitive voltage source, meansconnecting said voltage source directly to said spark bridge comprisinga substantially non-inductive circuit to produce a substantiallyaperiodic spark discharge, whereby the fuel substance within the chamberis ignited, propelled through said orifice and atomized, said sparkbridge comprising opposing electrodes separated by a continuous bridgeof semiconductive insulating material to form a fuel contacting creepspark supporting surface thereon, one of said electrodes comprising acentral rod-like member and the other of said electrodes comprising acylindrical member surrounding said rod-like member, the cylindricalmember having an end portion extending beyond and spaced from thecorresponding ends of said central member and of the insulation to formsaid chamber and said narrow orifice.

2. A device for atomizing and igniting a liquid fuel substance andcomprising means forming a pressurizing chamber having at least onenarrow orifice connecting the interior of said chamber with thesurrounding atmosphere, and permitting entrance of atmospheric air intothe chamber, means for supplying to the chamber the liquid fuelsubstance to be atomized and ignited, said chamber and orifice being soproportioned and arranged as to allow the simultaneous presence of airand said fuel substance, a substantially non-inductive spark bridge insaid chamber and adjacent said fuel supplying means to contact a portionof said fuel, said spark bridge comprising two electrodes and meansforming a semi-conductive fuel contacting spark creep surface disposedtherebetween, a unidirectional capacitive voltage source, meansconnecting said voltage source directly to said spark bridge comprisinga substantially non-inductive circuit to produce a substantiallyaperiodic spark discharge, whereby the ignition of the substance isstarted within the chamher to propel the ignited substance through saidorifice.

3. A device according to claim 2 wherein one of said electrodescomprises a central rod-like member and the other of said electrodescomprises a cylindrical member surrounding said rod-like member.

4. A device according to claim 2 wherein said spark bridge has at. leastone duct passing substantially longitudinally through said spark bridgeand forming a part of said means for supplying said liquid to beatomized.

5. A device according to claim 2 wherein said spark bridge has a helicalduct passing substantially longitudinally through said spark bridge andforming a part of said means for supplying said liquid to be atomized.

6. A device according to claim 2 in which one of said electrodescomprises a central rod-like member and the other of said electrodescomprises a cylindrical member surrounding said rod-like member, therod-like member having a central bore therethrough forming part of saidmeans for supplying said liquid to the pressurizing chamber.

7. A device according to claim 2 in which one of said electrodescomprises a central, rod-like member and the other of said electrodescomprises a cylindrical member surrounding said rod-like member, saidcentral electrode and the semi-conductive material being formed toprovide at least one duct forming part of said means for supplying saidliquid to be atomized.

8. A device according to claim 2 in which one of said electrodescomprises a central rod-like member and the other of said electrodescomprises a cylindrical member surrounding said rod-like member, saidinsulating material and said outer electrode being spaced to provide atleast one duct forming part of said means for supplying said liquid tobe atomized.

9. In a device according to claim 1, wherein the means for supplying tosaid chamber the substance to be atomized and ignited includes at leastone duct provided between said ccntralelectrode and the insulatingmaterial for the passage of liquid to said chamber.

10. In a device according to claim 1, wherein the means for supplying tothe spark chamber the substance to be atomized and ignited includes atleast one duct provided between said insulating material and said outerelectrode for the passage of liquid to said chamber.

References Cited in the file of this patent UNITED STATES PATENTS963,711 Jeffery July 5, 1910 1,376,180 Wickersham Apr. 26, 19211,905,957 Anderson Apr. 25, 1933 2,090,039 Goddard Aug. 17, 19372,125,035 Smits July 26, 1938 2,487,353 McLemore Nov. 8, 1949 2,567,037Smits Sept. 4, 1951

2. A DEVICE FOR ATONIZING AND IGNITING A LIQUID FUEL SUBSTANCE ANDCOMPRISING MEANS FORMING A PRESSURIZING CHAMBER HAVING AT LEAST ONENARROW ORIFICE CONNECTING THE INTERIOR OF SAID CHAMBER WITH THESURROUNDING ATMOSPHERE, AND PREMITTING ENTRANCE OF ATMOSPHERIC AIR INTOTHE CHAMBER, MEANS FOR SUPPLYNG TO THE CHAMBER THE LIQUID FUEL SUBSTANCETO BE ATONIZED AND IGNITED, SAID CHAMBER AND ORIFICE BEING SOPROPORTIONED AND ARRANGED AS TO ALLOW THE SIMULTANEOUS PRESENCE OF AIRAND SAID FUEL SUBSTANCE, A SUBSTANTIALLY NON-INDUCTIVE SPARK BRIDGE INSAID CHAMBER AND ADJACENT SAID FUEL SUPPLYING MEANS TO CONTACT A PORTIONOF SAID FUEL, SAID SPARK BRIDGE IN PRISING TWO ELECTRODES AND MEANSFORMING A SEMI-CNDUCTIVE FUEL CONTACTING SPARK CREEP SURFACE DISPOSEDTHEREBETWEEN, A UNIDIRECTIONAL CAPACITIVE VOLTAGE SOURCE, MEANSCONNECTING SAID VOLTAGE SOURCE DIRECTLY TO SAID SPARK BRIDGE COMPRISINGA SUBSTANTIALLY NON-INDUCTIVE CIRCUIT TO PRODUCE A SUBSTANTIALLYAPERIODIC SPARK DISCHARGE, WHEREBY THE IGNITION OF THE SUBSTANCE ISSTARTED WITHIN THE CHAMBER TO PROPEL THE IGNITED SUBSTANCE THROUGH SAIDORIFICE.